JP2003147767A - Rotational burying method for ready-made pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burying method for a ready-made pile for reducing an excavating removal earth quantity, and safely and surely transmitting an upper load to the ground. SOLUTION: This rotational burying method of the ready-made pile is characterized in that removal earth is excavated in a small quantity in a diameter less than a spiral blade diameter of the ready-made pile up to the prescribed depth by a preauger construction method, the tip vicinity of an excavation hole is expansively excavated, and is formed as a soil cement shape by injecting cement milk, and then, the ready-made pile having a spiral blade in the pile tip part vicinity is rotatably pressed in the expanded excavation hole, and the spiral blade is fixed and buried in the expanded excavation hole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of burying prefabricated piles, particularly to reduce the amount of excavated soil discharged from construction sites as much as possible in consideration of the environment, and to obtain high bearing capacity after burying prefabricated piles. Regarding the method of burying piles. More specifically, the present invention relates to a method of constructing a composite structure of ready-made piles and soil cement that can reduce excavation and soil discharge during construction and can obtain high bearing capacity after burying existing piles.

[0002]

2. Description of the Related Art Conventionally, in the pre-built embedded pile method of prefabricated piles, a pre-boring expansion root consolidation method has been often carried out in which the pile tip is enlarged and excavated and cement milk is injected into this portion to form an enlarged bulb at the pile tip. (Fig. 2). However, since the bearing capacity of the pile tip is smaller than that of the driving method and is insufficient, we have made ST piles with only the pile tip a large diameter and knotted piles with protrusions around the pile tip, A method (FIG. 3) of increasing the supporting force by adding a surface friction force has also been proposed.
However, in this method, the outer diameter of the pile has a convex portion and a large diameter portion, so in order to lay the pile by the embedded pile method, the excavation hole is excavated over the entire length of the pile with a diameter larger than the large diameter portion of the pile, and the excavated soil It is necessary to remove as much water as possible from the inside of the excavation hole, and to fluidize and soften the inside of the excavation hole in order to bury the piles. It was necessary to fluidize while injecting cement milk.

As a result, a large amount of earth and sand is discharged during excavation and burying of piles, and these become industrial wastes, which poses many environmental problems. In addition, JP-A-60-2
No. 38515 discloses a method in which a pile having spiral blades at the tip of the pile is rotationally inserted into a pile burying hole filled with soil-solidified cement milk to embed it to enhance the pile supporting force. However, this method focuses on improving the bearing capacity and fills the soil-solidified cement milk into the pile burial hole.Therefore, much earth and sand are discharged during excavation and burial, and there are similar problems. Was.

[0004]

DISCLOSURE OF THE INVENTION The present invention reduces the amount of excavated earth and sand and improves the reliability of the supporting force at the bottom of an excavated hole.
An object of the present invention is to provide a method for burying existing piles that can safely transfer the upper load to the ground and obtain a high bearing capacity after burying the piles.

[0005]

The present invention has arrived at the present invention, focusing on the skillful use of the rotary-depositing function of a spiral blade and the root-setting function of cement milk for manifesting a supporting force. That is, the present invention is a pre-auger method to excavate less soil to a predetermined depth with a diameter less than the spiral blade diameter of the prefabricated pile, expand and excavate the vicinity of the tip of the excavation hole, and inject cement milk into a soil cement shape. After that, the method for rotating and burying a ready-made pile is characterized in that a pre-formed pile having a spiral wing near the tip of the pile is press-fitted into the enlarged excavation hole and the spiral blade is fixed and embedded in the enlarged excavation hole. .

In particular, making the diameter of the upper excavation hole by the pre-auger smaller than the diameter (diameter) of the spiral blade of the pile excavates less soil, and even if soil is left in the excavation hole, the spiral blade is inserted into the excavation hole by rotary press-fitting. This was achieved based on the finding that existing ready-made piles could be easily buried. The upper drilling hole diameter is preferably the spiral blade diameter D-0.2 of the prefabricated pile.
The diameter is preferably D or less, more preferably D-0.5D or less. More preferably, the diameter of the spiral blade is D-0.5D or less, and the diameter is greater than or equal to the large diameter of the pile body. Most preferably, the diameter is the same as the large diameter of the pile body.

The present invention will be described in detail below with reference to the drawings. FIG. 1 shows an outline of this method. 1 shown in FIG. 1 is a pile main body, and 3 is a spiral blade fixed to the pile main body. Two
A pre-auger hole having a diameter equal to or smaller than the spiral blade diameter, and 5 is an enlarged drilling hole larger than the pre-auger diameter. Soil cement is filled in the enlarged excavation hole and integrated with the pile to form a composite structure. The bottom of the excavator used for constructing this structure is an auger bit, and the top is a rod having no bending and high rigidity. The auger bit at the tip may have any shape as long as it has an enlarged digging blade, even if the enlarged digging blade is hydraulically opened and closed mechanically, or it is opened and closed by resistance to the surrounding soil by reverse rotation. A system may be used. Further, it is necessary that the tip of the bit has a nozzle and has a structure capable of discharging the drilling liquid and the cement milk.

Using such an excavating device, an excavating hole is provided up to a predetermined depth by a normal pre-auger method. At this time, excavation may be performed while injecting drilling fluid such as water or bentonite mud, or when the ground is soft, it is preferable to perform excavation without using the excavating fluid or the like to reduce the amount of soil discharged by excavation. Then, the enlarged excavating blade is expanded to excavate the vicinity of the tip, and cement milk is injected through a nozzle or the like at the tip of the bit to make the inside of the enlarged excavation hole into soil cement.
After pulling out the excavator, a ready-made pile having a spiral blade near the tip of the pile in the drill hole is lowered by rotation to fix the spiral blade of the ready-made pile in the enlarged drill hole.

The diameter of the excavation hole may be selected according to the hardness of the ground. Since there are spiral blades near the tip of the pile, if the diameter of the excavation hole is soft, such as when the ground is smaller than the outer diameter of the pile body, it is possible to rotate and settle with the spiral blade. If the diameter of the drilled hole is equal to or larger than the diameter of the spiral blade, the propulsive force due to the rotation of the spiral blade becomes smaller because the ground becomes relatively soft. As a result, when the diameter of the spiral blade is small, the resistance at the tip of the pile exceeds the propulsive force due to the rotation of the spiral blade, making it difficult to sunk the pile even if the pile is rotated. is necessary.

The length of the enlarged excavation hole may be selected according to the type of ground and the required supporting force. About 3 times the blade diameter is enough, but 5 times or more is sufficient. Also, the diameter of the enlarged drill hole should be about the diameter of the blade, but if the ground is hard,
It may be slightly smaller than the blade diameter. In addition, when the excavator has sufficient capacity and a large expansion excavation is possible, it is desirable to make the diameter larger than the blade diameter. In order to sufficiently transmit the load from the blade to the expanded bulb, it is sufficient that the expanded excavation diameter is about 1.5 times the blade diameter.

The piles used may be steel pipe piles, ready-made concrete piles, steel pipe concrete piles, H-shaped steel piles and the like. In the case of ready-made concrete, it is necessary to take measures to attach the spiral blade to the outer peripheral surface of the pile. A plurality of short steel pipes may be installed in the formwork in advance during the production of concrete piles, and after the concrete is hardened, the spiral blade may be fixed to the steel pipe portion by welding. For the spiral wing attached to the tip of the pile, it is sufficient that the spiral makes one full revolution. When installing multiple spiral wings, install them at approximately equal intervals. Although the interval depends on the pile diameter, it is effective to install them at an interval of about 2 to 10 times the pile body diameter. The diameter of the spiral blade is preferably about 1.5 to 3 times the diameter of the pile body. If it is less than 1.5 times, the effect of distributing the load is small, and if it is more than 3 times, the blade's sharing force becomes large and the blade becomes thicker, and the resistance at the time of rotary deposition increases, which makes the deposition difficult.

At least one spiral blade may be mounted near the tip of the pile, but it is more effective if a plurality of spiral blades are mounted near the tip of the pile as shown in FIG. Further, as shown in FIGS. 4 and 5, it is more effective in terms of the bearing capacity performance of the pile if the pile main body is provided with irregularities to increase the adhesion between the soil cement in the enlarged excavation hole and the pile. Further, as shown in FIG. 6, the spiral blades may be provided at two locations above and below the enlarged excavation hole, and the intermediate portion thereof may be provided with irregularities on the pile body.

[0013]

As described above, according to the present invention, since it is possible to perform the rotary sedimentation, it is possible to reduce the amount of earth and sand discharged during excavation. Also,
After burying the pile, a high bearing capacity can be obtained, and if the spiral wing is made larger, the soil cement and the pile can be integrated, so that the load transfer of the pile becomes good. In the present invention, the excavation hole may be smaller than the spiral blade diameter even if a spiral blade larger than the pile outer diameter is attached, and if the spiral blade is made large, the enlarged excavation hole and the pile can be integrated, so the load of the pile Good communication. Moreover, since the excavation diameter can be made relatively small, the amount of discharged sludge can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of the present invention.

FIG. 2 is a schematic explanatory diagram showing an example of a conventional method.

FIG. 3 is a schematic explanatory view showing an example of a conventional construction method in which a knotted pile is used at the tip of the pile.

FIG. 4 is an explanatory view showing another embodiment of the present invention in which a protrusion is provided on the pile body.

FIG. 5 is an explanatory view showing another embodiment of the present invention in which a recess is provided in the pile body.

FIG. 6 is an explanatory view showing another embodiment of the present invention in which two spiral blades are provided and unevenness is provided in an intermediate portion thereof.

[Explanation of symbols]

1 pile body 2 Pre-auger hole on top 3 spiral wings 4 Soil cement hardened material 5 Expanded drill hole at the bottom

Claims (2)

[Claims] 1. A pre-auger method is used to excavate less soil to a predetermined depth with a diameter less than the spiral blade diameter of a prefabricated pile, expand the area near the tip of the excavation hole, and inject cement milk into a soil cement shape. After that, a prefabricated pile having spiral blades near the tip of the pile is rotationally press-fitted into the enlarged excavation hole, and the spiral blade is fixed and embedded in the enlarged excavation hole to be embedded therein. 2. The method according to claim 1, wherein the pre-auger method is used to excavate up to a predetermined depth with a spiral blade diameter D-0.2D or less of the prefabricated pile.